This invention relates generally to generators, and more particularly to wind turbine generators having replaceable bearings.
Recently, wind turbines have received increased attention as environmentally safe and relatively inexpensive alternative energy sources. With this growing interest, considerable efforts have been made to develop wind turbines that are reliable and efficient.
Generally, a wind turbine includes a rotor having multiple blades. The rotor is mounted to a housing or nacelle, which is positioned on top of a truss or tubular tower. Utility grade wind turbines (i.e., wind turbines designed to provide electrical power to a utility grid) can have large rotors (e.g., 30 or more meters in diameter). Blades on these rotors transform wind energy into a rotational torque or force that drives one or more generators that may be rotationally coupled to the rotor through a gearbox. The gearbox steps up the inherently low rotational speed of the turbine rotor for the generator to efficiently convert mechanical energy to electrical energy, which is fed into a utility grid.
Wind turbines including direct drive generators eliminate the gearbox, and reliability problems associated with the gearboxes. However, in at least some known geared wind turbines, both the generator and main bearings may prematurely fail. Because the direct drive generator bearings also function as the main bearings of the wind turbine, a means to readily replace the bearings is needed. To facilitate replacement of such bearings, at least one known direct drive wind turbine utilizes a single large-diameter bearing with a bolt-on flange. However, the combination of the large diameter and bolt-on flange causes the bearing to be expensive in comparison to other known bearing arrangements.
To facilitate reducing costs while optimizing turbine availability, bearing replacement should be performed rapidly at the wind turbine site with a minimal infrastructure and skill set required. However, known shrunk-on bearings used in direct drive wind turbines generally require change-out at the factory.